Are farm animals to blame for the rise of superbugs?

The over-use of antibiotics on animals has contributed to the growth of drug-resistant superbugs, many experts believe

Lettie Head is only 19, but has nearly died twice in the past two years from blood poisoning caused by an anti-biotic-resistant bug she picked up in hospital.

She hadn’t even been ill in the first place — she’d gone into hospital to have her baby delivered by Caesarean section. But not long after her son Zachary was born, she realised something was wrong.

‘I felt cold and was shaking,’ says the university student from Maidstone, Kent. ‘The nurse told me my blood pressure was right down.’

In fact, she’d developed a dangerous infection. By the time the doctors had worked out which bug was the culprit and started treatment, Lettie was barely conscious.

‘I had an oxygen mask, three drainage tubes coming out of my stomach, a feeding tube and a catheter in each arm giving me antibiotics and a blood infusion,’ she says.

She spent nearly three weeks in hospital. In fact, this was the second time she’d developed life-threatening blood poisoning, or sepsis, caused by a superbug. A year earlier, following the Caesarean delivery of her first son Henry, she had become ill.

‘I was hooked up to IV lines to get fluids into me quickly to raise my blood pressure. My hands began to swell up — I remember thinking I was going to burst,’ she says.

Each time the culprit was a bug resistant to standard antibiotics — doctors later told Lettie she was lucky to have survived.

What happened to her is a brutal reminder of how lucky we are to have antibiotics that can still treat superbugs.

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Without their protection, the death toll from infections could soar to Victorian levels, while routine operations such as hip replacements would be fraught with danger from untreatable infections, as the chief medical officer Professor Dame Sally Davies said recently. She described antibiotic resistance as a ‘catastrophic threat’ on a level with terrorism.

Last month, Health Secretary Jeremy Hunt announced the Government is preparing a five-year plan to tackle the problem.

The growth of drug-resistant superbugs is usually pinned on doctors — and, indeed, under the new plan, GPs will be warned not to hand out antibiotics like sweeties.

But a growing number of experts believe there’s another contributor to the problem: the over-use of antibiotics on animals.

Half of antibiotics used in this country go to animals, and experts fear farms are breeding grounds for antibiotic-resistant drugs. It’s claimed a combination of business interests and fears of damage to the livestock industry means this is being ignored, putting people’s lives at risk.

The problem is that the more an antibiotic is used — on humans or animals — the more resistant bacteria become to it.

‘As soon as you prescribe an antibiotic, you start creating resistance,’ says Dr Ron Daniels, head of the UK Sepsis Trust.

‘That is the way evolution works. The drug will kill off most of the bacteria it is targeting, but there will always be a few that survive because of something different in their genes that allows them to neutralise the drug.’

These survivor bacteria are the resistant ones and double in numbers every 20 to 30 minutes. ‘They flourish because their rivals, the others without the different gene, are dead,’ he says.

How farm bugs can be passed on to people

If an animal is carrying bacteria — antibiotic-resistant or not — these can pass to humans in an alarming number of ways.

‘One of the most common is eating infected meat,’ says Dr Daniels, also a consultant in intensive care medicine at the Good Hope Hospital, Birmingham.

‘Salmonella, E.coli and campylobacter cause hundreds of thousands of cases of food poisoning every year through eating infected meat or poor hygiene.

‘Bacteria on an uncooked carcass in a kitchen can get onto vegetables if they are chopped on the same board.’

Vegetables can carry bugs if grown in soil fertilised with animal waste.

There is the potential for bacteria to be passed in unpasteurised milk - two new strains of the MRSA superbug have shown up in British milk before it had been pasteurised

There is also the potential for bacteria to be passed in unpasteurised milk — two new strains of the antibiotic-resistant superbug MRSA have shown up in British milk before it had been pasteurised — which is worrying, as some people buy ‘raw’ milk because they think it’s healthier.

Not surprisingly, those most likely to pick up bugs from animals are people who work on farms, who then pass them to others.

The consequences of infection can be devastating. When a bug gets into your bloodstream — perhaps in childbirth, as a result of a wound or serious urinary tract infection — the result can be sepsis.

This is what Lettie Head suffered from, and it kills an estimated 37,000 Britons a year.

The risk is greater with a superbug. A new resistant strain of E.coli can cause cystitis and make you three times more likely to die if you develop sepsis.

The warnings that went ignored

Concern about superbugs has led to a battle about antibiotic use. Doctors want to reserve newer, more powerful antibiotics to save people in an emergency. But farmers want to use them on animals.

Ten years ago, a parliamentary committee warned that too many antibiotics were being used on farms, but the same quantities are still being used.

Furthermore, though hospital use of two of the best-known types of broad spectrum drugs (cephalosporins and the fluoroquinolones), which are effective against different bacteria, has been cut by a third, on farms their use has risen by 400 per cent and 70 per cent respectively since 2000.

The trouble with broad spectrum drugs is that by killing off lots of different strains of bacteria, it’s more likely that some of them will develop resistance.

Why farmers say they’re not to blame

Farming bodies claim resistant bugs found in farms rarely get into humans. They’re backed up by the Department for Environment, Food and Rural Affairs (Defra).

‘There is increasing scientific evidence that the use of antibiotics in animals is not a significant cause of resistance in bacteria that affect humans,’ says a spokesperson. ‘The clinical problems in humans are primarily the result of antibiotics used to treat human illnesses.’

But others disagree, including Dr Daniels and Dr Frank Aarestrup, head of the microbial genomics and antimicrobial resistance unit at the Danish Technical University in Copenhagen.

His campaign has cut antibiotic use on Denmark’s farms by 60 per cent since the mid-Nineties.

‘Anyone still opposing the link between antibiotic use in food and animal production and its direct impact on human health does so for other reasons beside health,’ he told The Lancet recently.

EU countries that have banned key farm antibiotics have lower levels of resistance to those drugs.

A type of antibiotic common on British poultry farms isn’t used to treat campylobacter infections in birds in Finland. Just 1 per cent of campylobacter infections in Finnish humans are resistant to antibiotics.

However, in Hungary and Spain, where
the drug is used heavily, 90 per cent of human infections are caused by
drug-resistant form of the campylobacter.

And,
according to a report from the World Health Organisation in 2011,
drug-resistant salmonella in humans is linked to farm animals — and, if
you are infected, your risk of dying within two years doubles.

Concern about superbugs has led to a battle about antibiotic use. Doctors want to reserve newer, more powerful antibiotics to save people

Reducing the use of antibiotics by doctors is recognised as vital for stopping the spread of resistant strains. But if animal use isn’t cut as well, farms can act as a reservoir of drug-resistant bacteria.

Farmers view with alarm attempts to impose controls on their freedom to use antibiotics. Gwen Jones is a dairy farmer in West Sussex with a herd of 300 Friesian dairy cows that produce 7,000 litres of milk a day.

He relies on antibiotics to deal with the regular infection of the cows’ udders, known as mastitis.

‘We check every cow for any sign of mastitis before each milking,’ says Gwen. ‘If it shows up, they get 3g of a standard antibiotic, similar to the one used to treat breastfeeding mothers, injected into the teat once a day, for four days.’

Though mastitis must be treated, he has no interest in using more antibiotics than necessary because they are expensive and, while the cow is being treated, its milk can’t be used.

‘You can’t have the sort of drop in drug use that Denmark claims unless there has been serious over-use beforehand,’ he says. ‘Healthy conditions are the key to keeping down antibiotic use.

‘We can control the situation much better than doctors — we don’t have cows demanding them for a sniffle, and we have to pay for these expensive drugs. We can make sure our patients finish the dose. Doctors can’t do that.

‘We don’t have sick cows that need a lot of antibiotic treatments. They get culled. GPs can’t do that.’

How vets cash in by doling out drugs

However, not all dairy farmers are as conscientious as Gwen.

Dairy calves are known to harbour a high level of antibiotic resistant E.coli bugs. A report has suggested this could be because farmers are feeding them on milk laced with antibiotics that should have been thrown away because it comes from cows being treated for mastitis.

Pigs and poultry account for nearly 90 per cent of the farm use of these drugs.

The vast majority of piglets and chicks get put on antibiotics from birth because the conditions they are raised in puts them at raised risk of infection.

‘Governments have routinely ignored the link between antibiotic resistance and the excessive use of drugs on factory farms,’ says Tory MP Zac Goldsmith. ‘It’s time there was a ban on routine use of antibiotics for prevention in poultry flocks.’

Dr Mark Holmes discovered the two new MRSA strains in unpasteurised milk. He has a lot of sympathy for good farmers such as Gwen Jones, but stresses that many other countries accept resistant bugs from animals can create problems for humans.

He is also worried there is an incentive for vets to prescribe drugs because they also sell them.

He also points out that ‘when you’re faced with infected animals and you know the farmer is under financial pressure, you are going to use the antibiotic that will be most effective at getting the animals producing again, even if it is one that’s vital for saving human lives.

‘It is unfair for the regulatory authorities to expect vets and farmers to take the long view when selecting antibiotics.’

How do we solve the problem?

Writing about the Danish scheme in science journal Nature, he said: ‘Preventing vets from profiting from drug sales had a huge impact on the overuse of antibiotics.’

But the vets didn’t lose money — they were paid to monitor the level of antibiotic use by farmers.

The data they provided allowed the Danish Agriculture Ministry to start issuing ‘yellow cards’ in 2010 to farmers using high levels of antibiotics. The result was a reduction of 25 per cent in two years.

Something similar should happen here, says the Alliance to Save Our Antibiotics, a campaigning group formed by three charities critical of factory farming.

The problem is that the industry ‘doesn’t seem committed to cutting back on drugs,’ says Richard Young, who is livestock expert with the Soil Association, one of the charities involved.

For instance, Britain is the only country in the EU that allows drug companies to advertise antibiotics for animals.

‘This can only have the effect of increasing sales,’ says Young. (Under pressure from the EU, this will change later this year.)

In Denmark, there is a system to monitor antibiotic use and resistance in animals and humans.

‘It allowed us to see who was using too much and who was using the most dangerous class of drugs,’ says Dr Aarestrup.

But the budget of Britain’s industry regulator, the Veterinary Medicines Directorate, for monitoring resistance is being cut heavily.

Dr Daniels is in no doubt about the risks. ‘The relative lack of regulation around the way anti-biotics are used on animals is costing human lives,’ he says.

And Lettie Head is counting her blessings — each time she developed sepsis, doctors found the right drugs to destroy the superbug. ‘I was told if I’d been older, I wouldn’t be here,’ says Lettie.